Following a theme here, I also like the distinction made between crowdsourcing and citizen science by Yale-based astrophysicist and Galaxy Zoo founder Kevin Schawinski:

“We prefer to call this [Galaxy Zoo] citizen science because it’s a better description of what you’re doing; you’re a regular citizen but you’re doing science. Crowd sourcing sounds a bit like, well, you’re just a member of the crowd and you’re not; you’re our collaborator. You’re pro-actively involved in the process of science by participating.”

“Galaxy Zoo volunteers do real work. They’re not just passively running something on their computer and hoping that they’ll be the first person to find aliens. They have a stake in science that comes out of it, which means that they are now interested in what we do with it, and what we find.”

On the application of wikinomics to astrophysics:

“It’s a new way of doing science. Mass collaboration makes things possible that were impossible before, mostly because of the size of our data sets. You can analyze a data set with hundreds or perhaps thousands of objects by yourself or with a small team. But if the question you want to answer involves millions of images or objects then there is really only one answer to this question: public participation.”